minios: fix xenbus_rm() calls in frontend drivers

The commit "minios: refactor xenbus state machine" caused "/state" to
be appended to the local value of nodename. Previously the nodename
variable pointed to dev->nodename.

The xenbus_rm() calls were not updated to reflect this change, and
refer to paths that do not exist.

For example, shutdown_blkfront() for vbd 2049 would issue these calls:
    xenbus_rm(XBT_NIL, "device/vbd/2049/state/ring-ref");
    xenbus_rm(XBT_NIL, "device/vbd/2049/state/event-channel");

This patch restores the previous behavior, issuing these calls
instead:
    xenbus_rm(XBT_NIL, "device/vbd/2049/ring-ref");
    xenbus_rm(XBT_NIL, "device/vbd/2049/event-channel");

This causes frontend drivers to not be properly reset when PV-GRUB
exists. Some PV Linux drivers fail to re-initialize frontend devices
if PV-GRUB leaves them in this state.

Signed-off-by: Ben Cressey <bcressey@amazon.com>
Reviewed-by: Matt Wilson <msw@amazon.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
[msw: adjusted commit message to include consequences, split out
 changes into separate patches]
Signed-off-by: Matt Wilson <msw@amazon.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/extras/mini-os/netfront.c b/extras/mini-os/netfront.c
index dc29f14075..4e087a56ed 100644
--- a/extras/mini-os/netfront.c
+++ b/extras/mini-os/netfront.c
@@ -549,14 +549,14 @@ close:
     if (err) free(err);
     xenbus_unwatch_path_token(XBT_NIL, path, path);
 
-    snprintf(path, sizeof(path), "%s/tx-ring-ref", nodename);
-    xenbus_rm(XBT_NIL, path);
-    snprintf(path, sizeof(path), "%s/rx-ring-ref", nodename);
-    xenbus_rm(XBT_NIL, path);
-    snprintf(path, sizeof(path), "%s/event-channel", nodename);
-    xenbus_rm(XBT_NIL, path);
-    snprintf(path, sizeof(path), "%s/request-rx-copy", nodename);
-    xenbus_rm(XBT_NIL, path);
+    snprintf(nodename, sizeof(nodename), "%s/tx-ring-ref", dev->nodename);
+    xenbus_rm(XBT_NIL, nodename);
+    snprintf(nodename, sizeof(nodename), "%s/rx-ring-ref", dev->nodename);
+    xenbus_rm(XBT_NIL, nodename);
+    snprintf(nodename, sizeof(nodename), "%s/event-channel", dev->nodename);
+    xenbus_rm(XBT_NIL, nodename);
+    snprintf(nodename, sizeof(nodename), "%s/request-rx-copy", dev->nodename);
+    xenbus_rm(XBT_NIL, nodename);
 
     if (!err)
         free_netfront(dev);